In induction heating devices, an alternating magnetic field is generated by means of an induction heating coil and this alternating magnetic field induces eddy currents and causes remagnetization losses in a cooking vessel which is to be heated and has a base composed of ferromagnetic material, as a result of which the cooking vessel is heated.
The induction heating coil is a constituent part of a resonant circuit which comprises the induction heating coil and one or more capacitors. The induction heating coil is usually designed as a flat, helically-wound coil with associated ferrite cores and arranged, for example, beneath a glass-ceramic surface of an induction hob. In this case, the induction heating coil forms, in conjunction with the cookware to be heated, an inductive and a resistive part of the resonant circuit.
In order to drive or excite the resonant circuit, a low-frequency AC mains voltage with a mains frequency of, for example, 50 Hz or 60 Hz is first rectified and then converted into an excitation or drive signal with a high frequency by means of semiconductor switches. The excitation signal or the drive voltage is usually a rectangular voltage with a frequency in a range of from 20 kHz to 50 kHz. A circuit for generating the excitation signal is also called a (frequency) converter.